Unconventional subterranean formations (e.g., unconventional reservoirs) play an important role in hydrocarbon production. Unconventional reservoirs are continuous-type reservoirs containing large-scale reserves, including shale gas and shale oil reserves, coalbed methane (CBM), and tight gas reservoirs. Unlike conventional reservoirs, unconventional reservoirs require specialized production technology, such as massive fracturing treatments for shale reservoirs or dewatering CBM.
Extracting hydrocarbon from an unconventional reservoir can involve significant expenditures in several operational aspects. For example, for an extraction operation in a shale formation, notable costs are incurred relating to pressure pumping, contract drilling, line pipes, and drilling fluids. Before proceeding with these potentially massive and costly operations, production testing can be used to help operators better understand, analyze, and forecast production. Further, by better understanding the formation properties, operators can optimize simulated treatments, and design and implement more efficient and cost-effective treatments.
Understanding formation properties can be achieved by performing a variety of different types of tests. In addition to conventional well testing, other tests can be used to understand the mechanical properties of the rock, predict formation behavior, and to optimize hydraulic fracturing treatments. For example, fracture closure pressure, instantaneous shut-in pressure, fracture breakdown pressure, and the formation fracturing fluid leakoff coefficient can be determined using specialized tests before or after fracturing treatments. In another example, “minifrac” or diagnostic fracture injection tests (DFITs) can be used to estimate the permeability of a formation and the initial reservoir pressure.
Like reference symbols in the various drawings indicate like elements.